Most of existing wireless communication systems adopt cellular systems. In a cellular system, the whole system is divided into multiple cells, and the same time-frequency resources may be used in each cell or used in multiple cells that are separated from each other at a certain distance. When a whole network is divided into multiple cells, network planning needs to be performed. During the network planning, a position of each base station in the network, the number of cells corresponding to a base station, a cell identity (ID) of each cell, and other system information (including a carrier frequency, bandwidth, and the like) used by each cell need to be planned.
After the network planning is complete, each base station sends signals according to the cell system information that has been planned. When accessing the network, each user equipment needs to search for a cell and access the cell. Then, the user equipment reads other relevant system information of the cell from a broadcast channel and then establishes a communication connection with a base station according to the cell system information, such as a cell ID/carrier frequency of a carrier/system bandwidth/the number of antennas.
However, in a wireless communication system, after the network planning is complete, each cell ID and corresponding system information are fixed. Regardless of changes in user equipment distribution and service requirement distribution in a practical environment, only a cell system planned during the network planning can be used to provide a service for a user equipment, and cell system information in a network cannot be adjusted due to a change in user equipment distribution or service requirement distribution, so as to adjust a cell to adapt to the change.
For example, when one or more new cells are added to a network, network replanning needs to be performed for the whole network to allocate a cell ID to the new cell. If the new cell is a temporary cell or the cell position frequently changes, network replanning needs to be performed for each change. As a result, complexity of network maintenance increases. However, if the new cell is allowed to randomly select a cell ID by itself, it is likely to cause relatively large inter-cell interference or a situation that is not applicable to service distribution in the network.
For another example, in a network including a macro cell and a micro cell, if a main requirement of the network is to obtain more control channel capacities, the macro cell and the micro cell may be allowed to use different cell IDs. If the main requirement of the network is to obtain better inter-cell collaboration, the macro cell and the micro cell may be allowed to use a same cell ID. When the main requirement in the network changes, because a cell ID has been planned during the network planning and cannot be changed, the existing network cannot accommodate a change in the requirement.
In addition, when establishing a communication connection with a cell, a user equipment needs to establish initial downlink synchronization and synchronization tracking with a base station and receives, based on the synchronization, data sent by the base station, such as data of a physical downlink shared channel (PDSCH). In an uplink, the base station needs to indicate a certain timing advance (TA) for the user equipment, and the user equipment determines an uplink transmission moment according to accumulation of TAs received from the base station, a predefined offset value, and the downlink synchronization.
In dynamic node selection (DPS) transmission mode, the user equipment needs to establish synchronization with multiple nodes. However, the user equipment does not know reference signals according to which synchronization is performed, synchronization according to which a PDSCH is received, and synchronization according to which the uplink transmission moment is determined.